Electronic devices used with wireless communication systems, such as cellular phones, GPS receivers, and Wi-Fi enabled notebook and tablet computers, generally contain signal processing systems that have interfaces to the analog world. Such interfaces may include wire line and wireless receivers that receive transmitted power and convert the received power to an analog or digital signal that may be demodulated using analog or digital signal processing techniques.
In addition to having a radio frequency (RF) transceiver, many modern mobile communication platforms also use further front end components such as power amplifiers, active antenna tuners, low noise amplifiers, and antenna switches. Moreover, in multiple antenna systems, such as multiple input multiple output (MIMO) systems, and multiple protocol systems, the RF system may have a multitude of various selectable and configurable components that support each particular signal path and/or protocol. Many of these multiple radio frequency components are controllable by a digital bus in order to provide control and configuration in various operational modes.
One such digital interface bus is based on a standardized protocol developed by the MIPI Alliance called the radio frequency front-end (RFFE) control interface described in the “MIPI® Alliance Specification for RF Front-End Control Interface,” version 1.10-26 Jul. 2011, which is incorporated herein by reference in its entirety. The MIPI RFFE control interface bus contains its own power supply voltage, and data is transmitted via a CLK line and a DATA line. Each RFFE slave device coupled to the MIPI RFFE bus is identifiable via a slave identifier, a manufacturer identifier, and a product identifier. A relatively high clock frequency of 26 MHz is used to for the RFFE bus in order to facilitate timing-critical functionality across multiple devices.